The odd item out is "Rhythm". Euphemism, oxymoron, and hyperbole are all figures of speech, which are used in literature and everyday language to create certain effects. Euphemism is a way of expressing something unpleasant or offensive in a more polite or indirect way. Oxymoron is a figure of speech in which contradictory terms are combined for effect. Hyperbole is a figure of speech that involves exaggeration for emphasis or effect. On the other hand, rhythm is a musical term that refers to the pattern of beats or accents in a piece of music, and it is not a figure of speech.